J/A+A/606/A82 Observed chemical structure of L1544 (Spezzano+, 2017)
The observed chemical structure of L1544.
Spezzano S., Caselli P., Bizzocchi L., Giuliano B. M., Lattanzi V.
<Astron. Astrophys. 606, A82 (2017)>
=2017A&A...606A..82S 2017A&A...606A..82S (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Radio lines
Keywords: ISM: clouds - ISM: molecules - radio lines: ISM -
ISM: individual objects: L1544
Abstract:
We present the emission maps of 39 different molecular transitions
belonging to 22 different molecules in the central 6.25 arcmin2 of
L1544. We classified our sample in five families, depending on the
location of their emission peaks within the core. Furthermore, to
systematically study the correlations among different molecules, we
have performed the principal component analysis (PCA) on the
integrated emission maps. The PCA allows us to reduce the amount of
variables in our dataset. Finally, we compare the maps of the first
three principal components with the H2 column density map, and the
Tdust map of the core. The results of our qualitative analysis is
the classification of the molecules in our dataset in the following
groups: (i) the c-C3H2 family (carbon chain molecules like C3H
and CCS), (ii) the dust peak family (nitrogen-bearing species like
N2H+ ), (iii) the methanol peak family (oxygen-bearing molecules
like methanol, SO and SO2, (iv) the HNCO peak family (HNCO, propyne
and its deuterated isotopologues). Only HC18O+ and 13CS do not
belong to any of the above mentioned groups. The principal component
maps allow us to confirm the (anti-)correlations among different
families that were described in a first qualitative analysis, but also
points out the correlation that could not be inferred before. For
example, the molecules belonging to the dust peak and the HNCO peak
families correlate in the third principal component map, hinting on a
chemical/physical correlation.
Description:
Integrated emission maps of 39 molecular transitions towards the
pre-stellar core L1544, presented in the paper in figures A.1-A.5.
The emission maps towards L1544 have been obtained using the IRAM 30m
telescope (Pico Veleta, Spain) in three different observing runs in
October 2013, July 2015, and January 2017. We performed a 2.5'x2.5'
on-the-fly (OTF) map centred on the source dust emission peak
(RA2000=05:04:17.21, DE2000=+25:10:42.8). Position switching was
used, with the reference position set at (-180", 180") offset with
respect to the map centre. The EMIR E090 receiver was used with the
Fourier Transform Spectrometer backend (FTS) with a spectral
resolution of 50 kHz. The antenna moved along an orthogonal pattern of
linear paths separated by 8" intervals, corresponding to roughly one
third of the beam FWHM. The mapping was carried out in good weather
conditions (τ∼0.03) and a typical system temperature of
Tsys∼90-100K. The data processing was done using the GILDAS software
(Pety 2005) and CASA (McMullin et al. 2007). All the maps have been
gridded to a pixel size of " with the CLASS software in the GILDAS
package, this corresponds to 1/5-1/7 of the actual beam size,
depending on the frequency. The integrated intensities have been
calculated in the 6.7-7.7km/s velocity range
Objects:
-----------------------------------------
RA (ICRS) DE Designation(s)
-----------------------------------------
05 04 18 +25 11.1 L1544 = LDN 1544
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 83 37 List of fits maps
fits/* . 37 Individual fits maps
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See also:
J/A+A/555/A109 : 14N/15N isotopic ratio in L1544 (Bizzocchi+, 2013)
J/ApJ/833/176 : The magnetic field of L1544. I. NIR data (Clemens+, 2016)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 21 I2 --- Nx Number of pixels along X-axis
23- 24 I2 --- Ny Number of pixels along Y-axis
26- 27 I2 Kibyte size Size of FITS file
29- 46 A18 --- FileName Name of FITS file, in subdirectory fits
48- 83 A36 --- Title Title of the FITS file (1)
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Note (1): the quantum numbers and frequencies of the transitions are reported
in Table 1 in the paper. When more than one transition has been mapped for
the same molecule, the quantum numbers are also reported in the name of
the fits file.
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Acknowledgements:
Silvia Spezzano, spezzano(at)mpe.mpg.de
(End) Patricia Vannier [CDS] 19-Jul-2017